There is no timeout option for workflows at all.
It a feature request that comes up from time to time, but it has never been added.
But you say you have the option in the UI, so i fear we are talking about different things, can you show a screenshot of where you see it ?
this is a timeout, for how long the message will stay in message the queue, not the workflow.
if the robot is not running, this is how long it takes before you get a an error message telling you the robot is not responding